mathematicians rule

There are three men on a train. One of them is an economist, one is a logician and one of them is a mathematician. They have just crossed the border into Scotland and they see a brown cow standing in a field from the window of the train standing parallel to where they're sitting.The economist says, 'Look the cows in Scotland are brown'The logician says, 'No. There are cows in Scotland of which one, at least is brown.'And the mathematician says, 'No. There is at least one cow in Scotland, of which one side appears to be brown.'